THE PANAMA CANAL
ever, no one who has served on the canal
would try to make a definite prediction.
A picture of this slide before the water
was let in is shown on page 146.
Gold Hill is a hard trap rock, with a
volcanic neck extending down to an un
known depth, and is there to stay. On
either side of it, however, the strata were
very much disturbed and slides have oc
curred of all kinds of material, both clay
and rock. The slides on the north side
are nearly all of soft rock.
Colonel Gaillard, who had charge of
the work in Culebra Cut, never knew,
when he returned to work in the morn
ing, that tracks and shovels would be
found as left the night before. He strug
gled with the cut for six long years, until
it was practically completed, but finally
broke and died under the strain.
Two distinctive kinds of slides are en
countered in Culebra Cut. In one case
the entire body of material moves prac
tically on an inclined plane, this plane
being sometimes rock, sometimes clay.
The Cucaracha slide is of this character
and is called a true slide.
In slides of the other character, the
first indication is a crack in the bank,
sometimes 300 or 400 feet back from the
edge of the cut. This crack or break
opens, and the ground there will often
settle down before it does at the edge of
the cut. When the general movement
comes, the bottom of the cut comes up.
Steam shovels have been lifted by one of
these slides as much as 18 feet, with the
tracks hardly thrown out of alignment.
EARTHQUAKES AND THE CANAL
One of the great arguments against a
lock canal at Panama was the earthquake
argument, which prophesied that the
locks would inevitably be destroyed by
earthquake shocks. The picture shown
on page 179 is the answer to that argu
ment. It shows the famous flat arch in
the now ruined church of Santo Domingo
in Panama City, which has stood there
for more than 200 years. The existence
of this old and apparently unstable struc
ture is a proof that Panama is free from
serious earthquakes.
An examination of this arch, taken in
connection with the fact that it has stood
for the length of time it has, seems to
warrant the conclusion that Panama has
been more free from serious earthquakes
during the time in question than Tennes
see, Missouri, or Arkansas, when it is re
membered that Reel Foot Lake, in Ten
nessee, and the "Sunk Lands," in Mis
souri and Arkansas, along the basin of
St. Francis, were formed during an earth
quake in 1812, a little more than a cen
tury ago, while this structure has stood
for more than twice that period.
Panama has been visited by a few
earthquake tremors lately, one of them
being of sufficient intensity to cause vases
to fall from shelves, but careful examina
tion of the locks failed to show the slight
est cracks in the masonry, and the dam
showed no tendency to settle or change
its form in any way whatever. The cen
ter of the disturbances which produce the
tremors is usually about 200 or 300 miles
away. I do not know where the center
of these last disturbances was, but when
the serious earthquakes occurred in Costa
Rica two or three years ago, only slight
tremors were felt at Panama.
While I was away, in November, my
wife wrote me that there had been an
other little earthquake since I left. She
was upstairs and had a Jamaican woman
sewing at the time, and just as the house
commenced to shake the Jamaican wo
man fell down on her knees to pray.
While my wife believes in the efficacy of
prayer, she told the woman that the best
place to pray during an earthquake was
outside. The advice is thought to be
good.
THE GATUN LOCKS
All the essential features of the Gatun
locks are situated on rock. It is a soft
rock and was called indurated clay in the
first description of it; but people did not
understand what indurated clay meant,
and so the name was changed to argilla
ceous sandstone.
This stone is solid and makes a good
foundation when not exposed to the air.
If so exposed, however, it acts like shale
and goes to pieces. In making an exca
vation for the locks and as soon as grade
was reached, the foundation was imme
diately covered with concrete, thus re-
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